Electric heating unit.



T. VAN ALLER.

ELECTRIC HEATING UNIT.

APPLICATION FILED MAYll, 1908.

1,024,234. Patented Apr. 23, 1912.

'1|mil mm"!lllllllllll uiu llllIIIIll"Ilillllllllllll l l Witnesses: WInventor:

Tycho Van filler, @Z M 9 @W UNITED STATES PATENT OFFICE.

TYCHO VAN ALLER, OF SCHENECTADY, NEW YORK, ASSIGNOR T0 GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.

ELECTRIC HEATING UNIT.

Specification of Letters Patent.

Patented Apr. 23, 1912.

Application filed May 11, 1908. Serial No. 432,023.

is uniformly and evenly distributed in a simple and eflicient manner.

One of'the objects of my invention is to provide a unit which may bereadily adapted for heating various shaped surfaces, which may be easilymodified so as to adapt it for distributing the heat over an irregulararea, and which atthe same time can be applied to the part to be heatedwith a maximum of efliciency and simplicity.

In carrying out my invention I first wind the resistance conductor intothe form of a helix. I prefer to have this helix closed on itself so asto obtain a maximum heating surface. In order-that the turns of thehelix shall not come in electrical contact with each other, it isnecessary that the resistance c0nductor be insulated. For this purpose Iprefer to use a wire having an insulating oxid so that when the wire isheated up to a definite point a layer or coating of oxid is formedthereon which has insulating properties. The helixis then bent back andforth on itself so as to cover the desired area. When the unit hasacquired the desired form it is flattened on itself byvbeing rolled orpressed until the opposite sides of the helix are in contact. In thisway the effect of aflat strip is obtained without meeting thedifliculties which are found in bending a flat.

strip edgewise upon itself.

In the accompanying drawing I- have shown my invention embodied inconcrete form, Figure 1 showing the unit adapted for use on a flatiron,while Figs. 2" and 3 show a fragment of the coil before and after theflattening process respectively.

Referring to the drawing, the resistance wire 10 is first wound into aclosed helix as shown, although the turns of the helix may be spacedapart if desired. The particular wire used in this helix forms no partof my invention although I prefer to use a wire which when heated willbecome coated with an insulating oxid. Such a wire is disclosed in thepatent to John T. H. Dempster, No. 901,428, and contains nickel,chromium, manganese and iron. The wire may be heated to form the oxid bypassing a current through it, it being desirable to first separate theturns by drawing out the helix so that the current will pass from end toend of the wire. It is obvious that the wire may be coated with theinsulating oxid either before or after it is formed into a helix. Vhenthe helix is finally made it is laid upon the sursired shape isobtained, it is flattened by passing it through rollers, or by puttingit in a press or in any desired manner. means, substantially the sameresult is obtained as if the resistance conductor were in the form of astrip bent back and forth, that is, an excellent heat-conducting jointis produced. With the strip, however, it would be extremely difficult tomake the necessary bends, whereas with the helix the bending isaccomplished in a simple manner.

While I have described my invention in connection with specific steps ofa process of manufacture and arranged in a definite way, it should beunderstood that I do not wish to limit my invention thereto except in.so far as it is limited by the scope of the claimsannexed hereto.

What I claim as new and desire to secure by Letters Patent of the United:States, is,

1. A resistance unit comprising an insulated helical resistanceconductor flattened on itself and bent back and forth to cover a desiredarea. a

2. A'I'GSlStfiIlC unit comprising a flattened helical resistanceconductor bent back and forth in parallel lines to cover a desired area.

By this forth in parallel lines of unequal length to own metal, theopposite sides of each turn of cover a desired area. the coil being incontact with each other. 10 4. A resistance unit comprising an insu- Inwitness whereof, I have hereunto set latcd resistance conductor formedinto a my hand this 9th day of May, 1908. 5 closed flattened helix andbent back and TYCHO VAN ALLER.

forth to cover a desired area. Witnesses;

5. A resistance unit comprising a coil hav- BENJAMIN B. HULL,

ing a surface insulation of the oxid of its HELEN ORFORD.

